Pope Francis holds the pastoral staff as he celebrates an Easter vigil service, in St. Peter's Basilica, at the Vatican, Saturday, March 26, 2016. (AP Photo/Gregorio Borgia)

VATICAN CITY (AP) — Pope Francis concluded a bleak week in Europe with a message of hope during an Easter Vigil service Saturday, saying darkness and fear must not prevail and “imprison” the world with pessimism.

Francis’ call to hope on the eve of the most joyful celebration in the Christian calendar contrasted sharply with his sharp condemnation in recent days of the attacks in Belgium and elsewhere by Islamic extremists.

Francis entered the silent and darkened basilica with just a single candle guiding him at the start of the vigil. As he reached the altar, the basilica’s floodlights flipped on in a symbolic show of light after the darkness of Good Friday, which recalls Jesus’ death.

In his homily, Francis said the hope that Easter brings is a lesson for the Christian faithful to cast aside the pessimism that can “imprison” people inside of themselves.

“We see and will continue to see problems both inside and out. They will always be there,” he said. But he insisted: “Let us not allow darkness and fear to distract us and control our hearts.”

“Today is the celebration of our hope,” he said. “It is so necessary today.” The Easter message recalling Christ’s resurrection, “awakens and resurrects hope in hearts burdened by sadness,” he said.

The lengthy vigil service included a papal baptism for 12 adults hailing from China, South Korea and other countries around the world. Early Sunday, Francis will preside over Easter Mass and offer his annual Easter blessing.

During remarks Friday at the Colosseum capping the “Way of the Cross” procession re-enacting Jesus’ crucifixion, Francis denounced the “terrorist acts committed by followers of some religions which profane the name of God and which use the holy name to justify their unprecedented violence.”

While the pope was at the Colosseum, his chief alms-giver was out on the streets of Rome giving out sleeping bags to the homeless Friday night in a show of papal support for the city’s least fortunate.